(b) Sample collection
Typically, transient water samples are collected for groundwater investigation. For
monitoring wells in the same site, sampling should be conducted in a relatively
concentrated and small period of time which should be limited to three days.
Negative pressure pumps should not be used during groundwater sampling, in
order to avoid degassing of dissolved gases and loss of volatile organic compounds
(VOCs) to be tested. Samples should be taken as close as possible to wellbores,
with no or little contact with the atmosphere to avoid sample contamination, volatile
loss and morphological transformation.
The specific place that water samples are taken is determined by test items. For
example, water samples for DNAPL measurement should be taken from the lower
bed of aquifer or the upper bed of aquiclude, and those for LNAPL measurement
taken from the upper bed of aquifer.
Water samples for the measurement of VOCs and semi-volatile organic compounds (SVOCs) must fill the sample containers with no gap in the upper
part. Water samples for the determination of sulfides, oil, heavy metals, bacteria,
radioactivity and etc. should be collected separately.
Quality control of samples is required for each batch of water samples, including
but not limited to field duplicates and field blanks. Field duplicates should be no
less than 10% of the total samples and generally divided into at least two groups in
each batch. They should be randomly inserted into the entire batch rather than
continuously aligned. There are at least three field blanks in each batch of water
samples.
(3) On-site measurement
All items are measured on site if possible, including water level, temperature, pH,
conductivity, turbidity, chromaticity, flavor level, macroscopic objects, dissolved
oxygen, ORP and etc. Instrument must be calibrated before used for on-site measurement, and the measurement results truthfully reflected in the relevant forms.
(4) Sample storage
Sample containers should meet different material requirements, depending on test
items. For example, sodium ion samples should be stored in tetrafluoroethylene
(C 2 F 4 ) containers, and organic samples should be stored in glass containers.
Containers need to be cleaned before use.
After collected, samples should be transported in refrigerated storage tanks and
delivered to the testing laboratory as soon as possible.
Samples for different purposes are stored according to the corresponding conditions, and especially, organic samples must be stored exactly as required.
Normally, VOC water samples should be stored in bottles upside down and away
from light, at 4 °C within 7 days, and SVOC water samples stored away from light,
at 4 °C within 15 days.
2.2 Content of Investigation
27
Typically, transient water samples are collected for groundwater investigation. For
monitoring wells in the same site, sampling should be conducted in a relatively
concentrated and small period of time which should be limited to three days.
Negative pressure pumps should not be used during groundwater sampling, in
order to avoid degassing of dissolved gases and loss of volatile organic compounds
(VOCs) to be tested. Samples should be taken as close as possible to wellbores,
with no or little contact with the atmosphere to avoid sample contamination, volatile
loss and morphological transformation.
The specific place that water samples are taken is determined by test items. For
example, water samples for DNAPL measurement should be taken from the lower
bed of aquifer or the upper bed of aquiclude, and those for LNAPL measurement
taken from the upper bed of aquifer.
Water samples for the measurement of VOCs and semi-volatile organic compounds (SVOCs) must fill the sample containers with no gap in the upper
part. Water samples for the determination of sulfides, oil, heavy metals, bacteria,
radioactivity and etc. should be collected separately.
Quality control of samples is required for each batch of water samples, including
but not limited to field duplicates and field blanks. Field duplicates should be no
less than 10% of the total samples and generally divided into at least two groups in
each batch. They should be randomly inserted into the entire batch rather than
continuously aligned. There are at least three field blanks in each batch of water
samples.
(3) On-site measurement
All items are measured on site if possible, including water level, temperature, pH,
conductivity, turbidity, chromaticity, flavor level, macroscopic objects, dissolved
oxygen, ORP and etc. Instrument must be calibrated before used for on-site measurement, and the measurement results truthfully reflected in the relevant forms.
(4) Sample storage
Sample containers should meet different material requirements, depending on test
items. For example, sodium ion samples should be stored in tetrafluoroethylene
(C 2 F 4 ) containers, and organic samples should be stored in glass containers.
Containers need to be cleaned before use.
After collected, samples should be transported in refrigerated storage tanks and
delivered to the testing laboratory as soon as possible.
Samples for different purposes are stored according to the corresponding conditions, and especially, organic samples must be stored exactly as required.
Normally, VOC water samples should be stored in bottles upside down and away
from light, at 4 °C within 7 days, and SVOC water samples stored away from light,
at 4 °C within 15 days.
2.2 Content of Investigation
27