Environmental Sampling Techniques - Fundamentals of Environmental Sampling and Analysis - page 91

the impoundment. For large impoundments, the logistics, health and safety
concern of sampling will usually dictate whether to use boats, manlifts, or safety
lines.
There is not established sampling protocol for debris, since the irregular and/or
large pieces of materials such as metal, plastic, and wood present challenge both in
sampling and subsequent sample preparation. Sampling from waste piles such as
impoundment dredge or slag piles would be relatively easy. Depending on the
sampling objective, either grab sampling using a scoop/trowel or interior sampling
using an auger is appropriate. For large waste piles, EPA recommended a 3-ft depth
for representative samples.
Surface sampling is unique because of the technique and the way to express the
results. Surface sampling includes wipe, chip, and dust sampling depending on the
types of surface and materials to be collected. Wipe sampling is usually conducted in
a 100-cm 2 area on relatively smooth, nonporous surfaces such as wall, floors,
ventilation ducts and fans, empty transformers, process equipment, and vehicles
containing nonvolatile compounds. It is also typically used to determine if
decontamination has been effective or not (e.g., disposal facility, sampling
equipment). A piece of sterile medical gauze soaked with proper solvents (hexane,
methanol, water, nitric acid) is used. To collect, you wipe back and front, and
then side to side, to make sure you get the full area. The results are expressed in
m

g/100 cm 2 . The second method, chip sampling, is used to collect nonvolatile
species from porous surfaces including cement, brick or wood in areas such as floors
near process areas, storage tanks, and loading dock areas. Chip sampling is usually
performed with a hammer and chisel or with an electric hammer for a 1/8-inch
sampling depth. Subsequent laboratory analysis may require special grinding or
extraction procedures. Lastly, the dust sampling is used to collect metal and SVOCs
in residues or dust found on porous or nonporous surface in areas such as bagging,
processing, or grinding facitities where powdery contaminants and dust may have
been accumulated. Unlike the other two surface sampling methods, the results from
dust sampling are reported in weight/weight (mg/kg).

Practical tips
In almost all waste sampling cases, you need to get 40-h HAZWOPER
training before you can handle any hazardous materials. Safety and health
precautions are the most important! It is not worth it to do any work if the
work is not safe. Select the appropriate level of PPE and know how to use
them.
Special tools are needed to open drums. Use spark-free drum openers and
other suitable tools.
Sample with extreme cautions when dealing with containers of unknown
chemical identities. In some cases, the labels may not reflect the true
contents as drums may be recycled or chemicals have been degraded.
Cross contamination due to sampling tools and containers is of less concern
since analytes in hazardous materials are often present at high concentrations.