6.1
According to Section 7.5
of updated EM&A Manual, an ambient arsenic monitoring is required to be
conducted in KTN during the clean-up processes of arsenic containing soil and
the construction phase.
6.2
The Respirable Suspended
Particulate (RSP, or PM10) should be measured by High Volume Sampler (HVS)
equipped with PM10 selector following the "Reference Method for the
Determination of Particulate Matter as PM10 in the Atmosphere" Part 50
Chapter 1 Appendix J, Title 40 of the Code of Federal Regulations of the USEPA.
6.3
The Dust-laden air should
be drawn through PM10 HVS fitted with a conditioned pre-weighting filter paper,
at a controlled rate. After sampling for 24-hour (refer Section 9.5.5 for
details on measurement period), the filter paper with retained PM10
particulates shall be collected and returned to the laboratory for drying in a
desiccators followed by accurate weighting. 24-hour average RSP levels shall be
calculated from the ratio of the mass of PM10 particulates retained on the
filter paper to the total volume of air sampled.
6.4
The weighted filter paper
shall be prepared for arsenic testing through a "Hot Acid Extraction
Procedure". The extracted material shall be tested for arsenic by using
Inductively Coupled Plasma/Mass Spectrometry (ICP/MS). The extraction and
testing will be referenced to the following methods:
l
Compendium Method 1O-3.1
Selection, Preparation and Extraction of Filter Material, Center for
Environmental Research Information, Office of Research and Development, USEPA,
June 1999; and
l
Compendium Method 1O-3.5
determination of Metals in Ambient Particulate Matter using Inductively Coupled
Plasma/Mass Spectrometry (ICP/MS., Center for Environmental Research
Information, Office of Research and Development, USEPA, June 1999.
6.5
Ambient arsenic
monitoring was conducted at the monitoring station under the Work Contract, as
shown in Figure 5. Table 6.1 describes the locations of the
ambient arsenic monitoring station.
Table
6.1 Location of
Ambient Arsenic Monitoring station
|
EP. No |
Contract No. |
Monitoring Stations |
Location |
|
EP-466/2013 EP-467/2013/A EP-468/2013/A |
ND/2019/01 |
KTN-DMS-4A[1] |
Temporary Structure at Pak Shek Au |
|
EP-468/2013/A |
ND/2019/03 |
Remarks:
[1]:
Monitoring at original KTN-DMS-4 (originally proposed in the approved EM&A
Manual) was denied as no electricity supply. An alternative location (KTN-DMS-4A) was
proposed.
6.6
Table 6.2 summarizes the equipment used in the ambient arsenic
monitoring. Copies of calibration certificates are attached in Appendix C.
Table
6.2 Ambient Arsenic Monitoring Equipment
|
Monitoring Stations |
Equipment |
Model and Make |
Quantity |
|
KTN-DMS-4A |
Calibrator |
TISCH Model:
TE-5025A |
1 |
|
|
HVS Sampler (RSP) |
TISCH Model: TE-6070X |
1 |
6.7
Table 6.3 summarizes the monitoring parameters and frequencies of
ambient arsenic during the clean-up processes of arsenic-containing soil and
construction. The ambient arsenic monitoring schedule for the reporting month
is shown in Appendix D.
Table
6.3 Impact Ambient Arsenic Monitoring Parameters, Frequency and Duration
|
Parameters |
Frequency |
|
24-hr RSP (Ambient Arsenic) |
Once/ 6 days |
24-hour RSP Monitoring
Instrumentation
6.8
High volume samplers
(HVS) (GMW PM10 (TE6070X)) complete with appropriate sampling inlets was
employed for 24-hour RSP monitoring.
The sampler is composed of a motor, a filter holder, a flow controller
and a sampling inlet and its performance specification complied with that
required by USEPA Standard Title 40, Code of Federation Regulations Chapter 1
(Part 50).
6.9
The following guidelines
were adopted during the installation of HVS:
l
a horizontal platform with appropriate support to secure the
samplers against gusty wind was provided;
l
no two samplers was placed less than 2 meters apart;
l
the distance between the sampler and an obstacle, such as
buildings, was at least twice the height that the obstacle protrudes above the
sampler;
l
a minimum of 2 meters of separation from walls, parapets and
penthouses was required for rooftop samplers;
l
a minimum of 2 meters separation from any supporting
structure, measured horizontally was required;
l
no furnace or incinerator flue was nearby;
l
airflow around the sampler was unrestricted;
l
the sampler was more than 20 meters from the dripline;
l
any wire fence and gate, to protect the sampler, were not
cause any obstruction during monitoring;
l
permission was obtained to set up the samplers and to obtain
access to the
l
monitoring stations; and
l
a secured supply of electricity was needed to operate the
samplers.
Operating/analytical procedures
for the operation of HVS
l Prior to the commencement
of the dust sampling, the flow rate of the high volume sampler will be properly
set (between 1.1 m3/min. and 1.4 m3/min.) in accordance
with the manufacturer's instruction to within the range recommended in USEPA
Standard Title 40, CFR Part 50.
l The power supply was
checked to ensure the sampler worked properly. On sampling, the sampler was operated
for 5 minutes to establish thermal equilibrium before placing any filter media
at the designated air monitoring station.
l The filter holding frame was
then removed by loosening the four nuts and a weighted and conditioned filter
will be carefully centered with the stamped number upwards, on a supporting
screen.
l The filter was aligned on
the screen so that the gasket formed an airtight seal on the outer edges of the
filter. Then the filter holding
frame was tightened to the filter holder with swing bolts. The applied pressure
were sufficient to avoid air leakage at the edges.
l The shelter lid was
closed and secured with the aluminum strip.
l The timer was then
programmed. Information was
recorded on the record sheet, which included the starting time, the weather
condition and the filter number (the initial weight of the filter paper can be
found out by using the filter number).
l After sampling, the
filter was removed and sent to the Wellab Ltd. for
weighing. The elapsed time was also
recorded.
l Before weighing, all
filters were equilibrated in a conditioning environment for 24 hours. The conditioning environment temperature
was between 25°C and 30°C and not vary by more than ±3°C; the relative humidity
(RH) was < 50% and not vary by more than ±5%. A convenient working RH was 40%.
Weighing results were further analysis of RSP concentrations collected by each
filter.
6.10 The following maintenance/calibration was required for the
HVS:
l The high volume motors
and their accessories were properly maintained. Appropriate maintenance such as
routine motor brushes replacement and electrical wiring checking were made to
ensure that the equipment and necessary power supply were in good working
condition.
l High volume samplers were
calibrated at bi-monthly intervals using TE-5025A Calibration Kit throughout
all stages of the ambient arsenic monitoring.
6.11 Quartz filters of size 8” x 10” were labelled before
sampling. A HOKLAS accredited laboratory, Wellab
Ltd., is responsible for the preparation of 24-hr conditioned and pre-weighed
filter papers for the monitoring team.
The balance for weighting filter paper was regularly calibrated against
a traceable standard.
6.12 All filters, which were prepared by Wellab
Ltd., were equilibrated in the conditioning environment for 24 hours before
weighing. The conditioning
environment temperature was around 25 °C and not variable by more than ±3 °C;
the relative humidity (RH) was < 50% and not variable by more than ±5%. A convenient working RH was 40%.
6.13 Wellab Ltd. (HOKLAS
Registration No. 083), is responsible for the extraction and testing procedure
for Arsenic and comprehensive quality assurance and quality control programmes were conducted.
6.14 The ambient arsenic monitoring results are summarized in Table
6.4. Detailed monitoring results and test report are shown in Appendix E.
Table 6.4 Summary Table of
24-hour RSP Monitoring Results (Ambient Arsenic) during the Reporting Month
|
Monitoring Date |
Monitoring Station |
Concentration (ng/m3) |
Action Level (ng/m3) |
Limit Level, (ng/m3) |
|
03/10/2020 |
KTN-DMS-4A |
3.86 |
9.36 |
11.7 |
|
08/10/2020 |
2.36 |
|||
|
14/10/2020 |
2.16 |
|||
|
20/10/2020 |
2.80 |
|||
|
24/10/2020 |
6.21 |
|||
|
30/10/2020 |
5.47 |
6.15 All ambient arsenic monitoring was conducted as scheduled in
the reporting month. No Action/Limit Level exceedances were recorded.
6.16 Should project-related non-compliance of the criteria occur,
action in accordance with the Action Plan in Appendix J shall be carried out.