In accordance with the recommendations of the EIA,
mitigation measures have been proposed during the construction phase of the
Project. Details of the mitigation
measures are presented in Appendix E
- Implementation Schedule.
In accordance with the recommendations of the EIA,
water quality EM&A is required during dredging and
sandfilling
activities. In addition, baseline
water quality monitoring will be required prior to the commencement of
construction activities. The
following Section provides details of the water quality monitoring to be
undertaken by the ET to verify the distance of sediment plume dispersion and to
identify whether the potential exists for any indirect impacts to occur to
ecological sensitive receivers. The
water quality monitoring programme will be carried out
to ensure that any deteriorating water quality is readily detected and timely
action taken to rectify the situation. The status and locations of water quality
sensitive receivers and the marine works location may change after issuing this
Manual. If required, the ET in
consultation with the Contractor(s) will propose updated monitoring locations
and seek approval from the ER, the IEC and EPD.
Water Quality Parameters Measurements of Dissolved Oxygen (DO)
concentration (mg L-1), DO saturation (%), Salinity (mg L-1),
Temperature (ºC) and Turbidity (NTU) will be taken in situ by the ET at
monitoring stations identified below.
Water samples for the measurements of SS (mg L-1) and
chlorophyll-a (µg L-1) will also be collected for laboratory
analysis.
In addition to the water quality parameters, other relevant data will
also be measured and recorded in Water Quality Monitoring Logs (Appendix
C), including the location of the sampling stations, water depth,
time, weather conditions, sea conditions, tidal stage, current direction and
speed, special phenomena and work activities undertaken around the monitoring
and works area that may influence the monitoring results.
Observations on any special phenomena and work underway at the construction site
at the time of sampling will also be recorded.
For water quality monitoring, the following equipment will be
supplied and used by the ET. The use
of similar equipment is subject to prior approval from the IEC.
5.1.1
Monitoring Equipment and
Methodology
For water quality monitoring, the following equipment should be supplied and used by the environmental contractor.
· Dissolved Oxygen and Temperature Measuring Equipment - The instrument should be a portable, weatherproof dissolved oxygen measuring instrument complete with cable, sensor, comprehensive operation manuals, and should be operable from a DC power source. It should be capable of measuring: dissolved oxygen levels in the range of 0–20 mg L-1 and 0-200% saturation; and a temperature of 0-45 degrees Celsius.
It should have a membrane electrode with automatic temperature compensation complete with a cable of not less than 35 m in length. Sufficient stocks of spare electrodes and cable should be available for replacement where necessary (for example, YSI model 59 meter, YSI 5739 probe, YSI 5795A submersible stirrer with reel and cable or an approved similar instrument).
·
Turbidity Measurement Equipment – The instrument shall be
a portable, weatherproof turbidity-measuring instrument complete with
comprehensive operation manual. The
equipment shall use a DC power source.
It shall have a photoelectric sensor capable of measuring turbidity
between 0-1000 NTU (e.g. Hach model 2100P or an
approved similar instrument).
·
Salinity Measurement Instrument
- A portable salinometer capable of measuring salinity in the range of
0-40 ppm should be provided for measuring salinity of
the water at each monitoring location.
·
Water Depth Detector
- A portable, battery-operated echo
sounder should be used for the determination of water depth at each designated
monitoring station. A detector
affixed to the bottom of the work boat, if the same vessel is to be used
throughout the monitoring programme, is preferred.
·
Current Velocity and Direction – No specific equipment
is recommended for measuring the current velocity and direction. However, the contractor should seek
approval of their proposed equipment with the client prior to deployment.
·
Positioning Device
- A hand-held or boat-fixed type
digital Global Positioning System (GPS) with way point bearing indication or
other equipment instrument of similar accuracy, should be provided and used
during water quality monitoring to ensure the monitoring vessel is at the
correct location before taking measurements. GPS or the equivalent instrument,
calibrated at appropriate checkpoint (e.g. Quarry Bay Survey Nail at Easting
840683.49, Northing 816709.55) should be provided and used to ensure the
monitoring station is at the correct position before taking measurement and
water samples.
·
Water Sampling Equipment
- A water sampler, consisting of a
transparent PVC or glass cylinder of not less than two litres, which can be
effectively sealed with cups at both ends, should be used (Kahlsico
Water Sampler 13SWB203 or an approved similar instrument). The water sampler should have a positive
latching system to keep it open and prevent premature closure until released by
a messenger when the sampler is at the selected water depth.
All
in situ monitoring instruments should be checked, calibrated and
certified by a laboratory accredited under HOKLAS or any other international
accreditation scheme before use, and subsequently re-calibrated at monthly
intervals throughout all stages of the water quality monitoring. Responses of sensors and electrodes
should be checked with certified standard solutions before each use.
For the on-site
calibration of field equipment, the
BS 1427: 1993, Guide to Field and On-Site
Test Methods for the Analysis of Waters should be observed. Sufficient stocks of spare parts should
be maintained for replacements when necessary. Backup monitoring equipment should also
be made available so that monitoring can proceed uninterrupted even when
equipment is under maintenance, calibration etc.
Water samples for SS and chlorophyll-a measurements should be collected
in high density polythene bottles, packed in ice (cooled to 4° C without being frozen), and delivered to a HOKLAS laboratory as soon as
possible after collection.
All
laboratory work should be carried out in a HOKLAS accredited laboratory. Water samples of about 1,000 mL should be
collected at the monitoring and control stations for carrying out the laboratory
determinations. The determination
work should start within the next working day after collection of the water
samples. The analyses shall commence
within 24 hours after collection of the water samples. The analyses should
follow the standard methods as described in APHA
Standard Methods for the
Examination of Water and Wastewater, 19th Edition or later, unless
otherwise specified (APHA 2540D for SS).
The
submitted information should include pre-treatment procedures, instrument use,
Quality Assurance/Quality Control (QA/QC) details (such as blank, spike
recovery, number of duplicate samples per-batch etc), detection limits and
accuracy. The QA/QC details should
be in accordance with requirements of HOKLAS or another internationally
accredited scheme.
5.1.2
Monitoring Stations
The monitoring station locations have
been established to identify potential impacts to water quality sensitive
receivers which are shown in
Figure 5.1.
Prior to, during and after the dredging and sandfilling works, water quality
sampling will be undertaken at stations situated around the dredging area and at
the sensitive receivers. The
monitoring at those stations is to ensure the dredging and sandfilling works of
the Project will not cause deterioration in water quality outside the impact
(mixing) zone, in particularly at the nearby sensitive areas (shown in
Figure 5.1).
·
R1 is a Reference Station
located to the south of the dredging/sandfilling area, which is not supposed to
be impacted by the dredging/sandfilling works. R1 is a representative station for the
background water quality for
·
R2 is a Reference Station located to the southwest of the
dredging/sandfilling area, which is not supposed to be impacted by the
dredging/sandfilling works. R2 is a representative station for the background
water quality in the Plover Cove region;
·
I1, I2 and I3 are the Impact Stations just outside the
mixing zone, which is unlikely to be impacted by the dredging/sandfilling works;
·
FCZ1 represents the Sensitive
Receiver located at the Yim Tin Tsai East Fish Culture
Zone, which is about 1.5 km to the southwest of the dredging/sandfilling area.
Deterioration of water quality at this station is not anticipated;
·
M1 represents the Sensitive
Receiver located at the Ting Kok SSSI, which is about
800 m to the west of the dredging/sandfilling area. Deterioration of water quality at this
station is not anticipated;
·
W1 represents the Sensitive
Receiver located at the Water Sport Centre, which is about 250 m to the
southeast of the dredging/sandfilling area, which is unlikely to be impacted by
the dredging/sandfilling works.
·
G1 is the Gradient Station to
assist in the identification of the source of any impact.
The
suggested co-ordinates of these monitoring stations are listed in
Figure 5.1.
The
monitoring stations will be sampled during Baseline Monitoring (prior to the
dredging works), Impact Monitoring (during dredging and sandfilling works) and
Post Construction Monitoring (after completion of sandfilling work).
5.1.3
Monitoring Frequency
For
baseline, impact and post-project monitoring, monitoring should be undertaken 3
days per week, at mid-flood and mid-ebb tides, with sampling/ measurement at the
designated stations. The intervals
between 2 consecutive sets of monitoring should not be less than 36 hours except
where there are exceedances of Action and/or Limit
Level, in which case monitoring frequency should be increased.
The tidal range for each of the flood and ebb tide should not be less than 0.5m.
The
water quality sampling will be undertaken within a 3-hour window of 1.5 hour
before and 1.5 hour after mid flood and mid-ebb tides. The Environmental Team will be
responsible for liaison with the engineering contractor to confirm whether
dredging/sandfilling works are being undertaken during the water quality
sampling.
Measurements shall be
taken at 3 water depths: 1m below water surface, mid-depth and 1m above sea bed,
except where the water depth less than 6m, the mid-depth station may be omitted.
Should the water depth be less than 3m, only the mid-depth station will be
monitored. The ET Leader shall seek approval from
the IEC and DEP on all the monitoring stations.
Replicates in-situ measurements and samples collected from each independent sampling event are required for all parameters to ensure a robust statistically interpretable dataset.
5.1.4
Baseline Monitoring
Baseline Monitoring will comprise sampling 3 days a week, at mid-flood and
mid-ebb tides, for at least 4 weeks prior to the commencement of the dredging
works. There shall not be any marine
construction activities in the vicinity of the monitoring stations during the
baseline monitoring. The monitoring will be undertaken at the specified eight
stations in total, as shown in
Figure 5.1. The intervals between 2 consecutive sets
of monitoring should not be less than 36 hours. The baseline monitoring schedule should
be provided to EPD for agreement at least 2 weeks prior to commencement of the
baseline monitoring work.
5.1.5 Impact Monitoring
Impact Monitoring will comprise sampling 3 days a week, at mid-flood and mid-ebb
tides, during the dredging and sandfilling works. The monitoring will be undertaken at the
specified eight stations as the Baseline Monitoring stations, as shown in
Figure 5.1.
The intervals between 2 consecutive sets
of monitoring should not be less than 36 hours except where there are exceedances of Action and/or Limit Levels, in which case the
monitoring frequency may be increased.
The monitoring results should be included in the EM&A reports.
5.1.6
Post-Project Monitoring
Upon the completion of the sandfilling works, Post-project
Monitoring shall be conducted for 4 weeks in the same manner as the Baseline
Monitoring.
5.1.7 Compliance /
Action Event Plan
Water quality monitoring results will be evaluated against Action and Limit
levels shown in Table 5.1.
Table 5.1 Action and Limit Levels for Water Quality (based on the Results of the Baseline Report)
Parameter |
Action |
Limit |
SS in mg L-1 (depth-averageda)c
|
95%-ile of baseline data, or 20% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day | 99%-ile of baseline data, or 30% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day and specific sensitive receiver water quality requirements |
Chlorophyll-a in µg L-1c |
Surface, Middle and Bottom 95%-ile of baseline data |
Surface, Middle and Bottom 10µg L-1 or 99%-ile of baseline data |
DO in mg L-1 bd |
Surface and Middle 5%-ile of baseline data for surface and middle layer Bottom 5%-ile of baseline data for bottom layers |
Surface, Middle 4mg L-1or 1%-ile of baseline for surface and middle layer Bottom 2mg L-1or 1%-ile of baseline data for bottom layer |
Turbidity in NTU (depth-averageda)c |
95%-ile of baseline data, or 20% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day | 99%-ile of baseline data, or 30% exceedance of value at any impact station and sensitive receiver compared with corresponding data from reference stations at the same tide of the same day |
Notes:
(a) “Depth-averaged” is calculated by taking the arithmetic means of reading of all three depths.
(b) For DO, non-compliance of the water quality limits occurs when monitoring result is lower than the limits.
(c) For SS, chlorophyll-a and turbidity, non-compliance of the water quality limits occurs when monitoring result is higher than the limits.
(d) Both Action and Limit Levels for DO (surface and middle) in the FCZ1(Figure 5.1) are less than 5 mg L-1.
Actions to be taken in the event that the Action or Limit Levels are exceeded
are shown in Table 5.2.
Table 5.2
Event and Action Plan for Water Quality
EVENT |
ACTION |
||||||
ET |
IEC |
ER |
Contractor |
||||
Action Level being exceeded by one sampling day |
1.
Repeat in-situ measurement to confirm findings;
2.
Identify source(s) of impact;
3.
Inform the IEC and the Contractor;
4.
Check monitoring data, all plant, equipment and the
Contractor’s working methods;
5.
Discuss mitigation measures with the IEC and the
Contractor; |
1.
Discuss with the ET and the Contractor on the mitigation
measures;
2.
Review proposals on mitigation measures submitted by the
Contractor;
3.
Assess the effectiveness of the implemented mitigation
measures. |
1.
Discuss with the IEC on the proposed mitigation measures;
2.
Make agreement on the mitigation measures to be
implemented. |
1.
Inform the ER and confirm notification of the
non-compliance in writing;
2.
Rectify unacceptable practice;
3.
Check all plant and equipment;
4.
Consider changes of working methods;
5.
Discuss with the ET the IEC and propose mitigation measures
to the IEC and ER;
6.
Implement the agreed mitigation measures. |
|
||
Action Level being exceeded by more than one consecutive
sampling days |
1.
Repeat in-situ measurement to confirm findings;
2.
Identify source(s) of impact;
3.
Inform the IEC and the Contractor;
4.
Check monitoring data, all plant, equipment and
Contractor’s working methods;
5.
Discuss mitigation measures with the IEC and the
Contractor;
6.
Ensure mitigation measures are implemented; |
1.
Discuss with the ET and the Contractor on the mitigation
measures;
2.
Review proposals on mitigation measures submitted by the
Contractor accordingly;
3.
Assess the effectiveness of the implemented mitigation
measures. |
1.
Discuss with the IEC on the proposed mitigation measures;
2.
Make agreement on the mitigation measures to be
implemented;
3.
Assess effectiveness of the implemented mitigation
measures. |
1.
Inform the ER and confirm notification of the
non-compliance in writing;
2.
Rectify unacceptable practice;
3.
Check all plant and equipment;
4.
Consider changes of working methods;
5.
Discuss with the ET and the IEC and propose mitigation
measures to the IEC and ER within 3 working days;
6.
Implement the agreed mitigation measures. |
|
||
Limit Level being exceeded by one consecutive sampling day |
1.
Repeat in-situ measurement to confirm findings;
2.
Identify source(s) of impact;
3.
Inform the IEC, the Contractor and the DEP;
4.
Check monitoring data, all plant, equipment and the
Contractor’s working methods;
5.
Discuss mitigation measures with the IEC, the ER and the
Contractor;
6.
Ensure mitigation measures are implemented. |
1.
Discuss with the ET / Contractor on the mitigation
measures;
2.
Review proposals on mitigation measures submitted by the
Contractor and advise the ER accordingly;
3.
Assess the effectiveness of the implemented mitigation
measures. |
1.
Discuss with the IEC, the ET and the Contractor on the
proposed mitigation measures;
2.
Request the Contractor to critically review the working
methods;
3.
Make agreement on the mitigation measures to be
implemented;
4.
Assess the effectiveness of the implemented mitigation
measures. |
1.
Inform the ER and confirm notification of the
non-compliance in writing;
2.
Rectify unacceptable practice;
3.
Check all plant and equipment;
4.
Consider changes of working methods;
5.
Discuss with the ET, the IEC and the ER and propose
mitigation measures to the IEC and the ER within 3 working days;
6.
Implement the agreed mitigation measures. |
|
||
Limit Level being exceeded by more than one consecutive
sampling days |
1.
Repeat in-situ measurement to confirm findings;
2.
Identify source(s) of impact;
3.
Inform the IEC, the Contractor and DEP;
4.
Check monitoring data, all plant, equipment and
Contractor’s working methods;
5.
Discuss mitigation measures with the IEC, the ER and the
Contractor;
6.
Ensure mitigation measures are implemented;
|
1.
Discuss with ET and Contractor on the mitigation measures;
2.
Review proposals on mitigation measures submitted by the
Contractor and advise the ER accordingly;
3.
Assess the effectiveness of the implemented mitigation
measures. |
1.
Discuss with the IEC, the ET and the Contractor on the
proposed mitigation measures;
2.
Request Contractor to critically review working methods;
3.
Make agreement on the mitigation measures to be
implemented;
4.
Assess effectiveness of the implemented mitigation
measures;
5.
Consider and instruct, if necessary, the Contractor to slow
down or to stop all or part of the marine work until no exceedance of Limit
Level. |
1.
Inform the ER and confirm notification of the
non-compliance in writing;
2.
Rectify unacceptable practice;
3.
Check all plant and equipment;
4.
Consider changes of working methods;
5.
Discuss with the ET, the IEC and the ER and propose
mitigation measures to the IEC and the ER within 3 working days;
6.
Implement the agreed mitigation measures;
7.
As directed by the ER, slow down or stop all or part of the
construction activities. |
|
||
The
Post-Construction Phase is defined as after completion of construction works but
before the operation of the beach. No sewage and wastewater generated from the
beach building facilities will be discharged into the beach or marine
environment, water quality impact due to sewage and wastewater discharge from
the beach building facilities is not anticipated (refer to EIA Report Section
6).
5.2.1
E. coli Monitoring
Monitoring for E. coli is recommended
at the outfall of the eastern culvert and western channel within six weeks after
the completion of construction works.
The purpose of the monitoring is to investigate the characteristics of
E. coli
loading in the box culvert/channel and to establish
relationship with E.
coli
levels at
the beach. Samples will be collected
at the locations specified in Figure
5.2 at/near the outlet of the outfall when no influx of seawater occur
(e.g. during low tide). During the
same tide,
E. coli
samples should be
collected at EPD’s routine beach monitoring stations.
The sampling team should confirm the locations of EPD’s
routine monitoring stations prior to the commencement of any sampling events. In some occasions, it is not practicable
to take the samples at EPD’s routine monitoring
stations, for example, the water is too shallow. Then the sampling team should determine
the nearest sampling locations which should be as close to
EPD’s
stations as possible. The coordinates of all the sampling locations should be
recorded.
E. coli
samples should be stored in cool box
(4°C) during the sampling and
transportation and should be delivered to the HOKLAS accredited laboratory, or
equivalent, to determine the
E. coli
content in the sample.
Other water quality parameters, i.e., pH, Dissolved
Oxygen (DO) concentration (mg L-1), DO saturation (%), Salinity (mg L-1),
Temperature (ºC) and Turbidity (NTU) should be taken in situ by the sampling
team at same monitoring stations as for
E.Coli
measurements.
Observations such as and weather and beach conditions, should also be
recorded.
Sampling should be conducted twice per week within six weeks after the
completion of construction works.
5.2.2 Progress of DSD's Village Sewerage Projects
Implementation programme of the village sewerage projects should be monitored to achieve the target sewerage connection rate to communal sewers before the beach is put into operation.
5.3.1 Routine Monitoring of Beach Water Quality
EPD has well established a comprehensive water quality monitoring programme for all gazetted beaches to detect any deterioration of beach water quality, which will also be implemented in this Lung Mei bathing beach.
EPD's current monitoring programme requires all gazetted beaches are monitored at least three times per month during bathing seasons. During non-bathing seasons, gazetted beaches are monitored once per month. The monitoring data assists to detect any deterioration of beach water quality. In case the beach water quality tends to be deteriorated, EPD will continue monitoring of the beach water quality and provide Leisure and Cultural Services Department (LCSD) the monitoring data. In case the beach water quality tends to be deteriorated, LCSD will decide the most appropriate method of improving the beach water quality.
In case the beach water quality at Lung Mei tends to be deterioriated and
becomes not desirable for swimming, LCSD will close the beach temporarily until
the beach water quality becomes suitable for swimming.
EPD will continue monitoring the beach water quality and provide LCSD the
monitoring results.
5.3.2
Red Tides
In the event of red tide that may occur naturally, similar to the practice adopted for other gazetted beaches by LCSD, Lung Mei beach may be closed to swimmers in accordance with the relevant procedures.