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) |
|
05/01/2021 |
KTN-DMS-4A |
5.12 |
9.36 |
11.7 |
|
11/01/2021 |
5.94 |
|||
|
15/01/2021 |
3.90 |
|||
|
21/01/2021 |
7.01 |
|||
|
27/01/2021 |
7.66 |
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 K shall
be carried out.