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Environmental Sampling
Document Number: 228
Introduction
Environmental sampling is done whenever there is a need to
investigate contaminants in water, air or soil. Typical situations
include the testing of hazardous waste sites, runoff into lakes,
streams and rivers, and air emissions from industry. The Environmental
Protection Agency (EPA) has regulations and procedures regarding the
sampling, analysis, procedures and equipment used in testing for
possible contaminants.
The EPA has listings of chemicals and methods that must be used to
extract and analyze the chemicals from samples for determination of
contents and concentrations. These methods are found in 40 CFR part
136, Appendix A.
There are five lists of approved test procedures.
- Biological Test Procedures
- Inorganic Test Procedures
- Non-Pesticide Organic Compounds Test
- Pesticides Test
- Radiological Test Procedures
Each list breaks down the individual chemicals in a group that can
be tested, and gives the method that should be used for the tests.
These lists can be found in the 40 CFR 100-149, 136.3, Identification
of Test Procedures.
EPA Methods for the Analysis of Pollutants
Each of the five test procedures typically uses the same methods for
analyzing pollutants. The test procedures contain some or all of the
following 16 steps.
- Scope and Application
Lists the chemicals that can be determined by this method.
Specifies the type of test that is required for the determination
(i.e. gas chromatograph (GC), flame ionization detector (FID) or
mass spectrometer (MS)). Tells where to find method detection limit
(MDL).
- Summary of Method
Gives a description of the process used for the analysis, along
with detailed specifications on how to perform the analysis.
- Contamination & Interference
Covers possible reasons for interference, such as impurities in
the purge gas, and methods of cleaning equipment or special
equipment to use so contamination is reduced.
- Safety
Identifies precautions to be taken with the chemical being
tested and the reagents involved in the analysis. Also covers the
possible hazards associated with the chemicals involved.
- Apparatus & Materials
Specifies the type of equipment to be used in the capture of
samples. Also covers the type of equipment to use in the procedure.
- Reagents & Standards
Lists chemicals, measurements, formulas and instructions on the
use and preparation of reagents for the procedure.
- Calibration
Gives specific calibration instructions for the equipment being
used on the tests in the methods. Also covers preparation of the
calibration standards.
- Quality Assurance/Quality Control
Gives the EPA's minimum standards for quality control required
in laboratories for most methods. Also gives instructions for the
specific program. Quality Assurance/Quality Control must be an
on-going process with written documentation.
- Sample Collection, Preservation and Handling
Identifies containers and tools needed for collection. Explains
storage requirements and storage time limits for collected samples.
- Procedures
Lists procedures to follow, along with measurements and time
limits to use when extracting samples.
- Performance Tests
Performance tests must be run on the testing equipment before
each 8-hour shift or at the beginning of the work day. Only after
these tests have been run according to the specific method can
samples and blanks be analyzed.
- Sample Purging and Gas Chromatograph
Gives procedures for purging samples from test equipment.
- Cleanup and Separation
Explains suggestions for cleanup and separation procedures.
- Gas Chromatograph/Flame Ionization Detector
Chroma-tography/High Performance Liquid Chromatography
Summarizes recommended operating conditions, retention times
and MDL for when gas apparatus are to be used.
- Calculations
Gives the calculation to be used for the method. Includes
factors and equations to be used.
- Method of Performance
Explains the Method Detection Limit (MDL) (Defined as the
minimum concentration of substance that can be measured and reported
with 99% confidence that the value is above zero) along with test
procedures, and how the EPA arrived at the MDL. Tables with the MDLs
of specific chemicals are shown for reference.
When sampling soil, water and air, many different types of equipment
are used. A typical tool used for taking soil samples is a
hand-operated auger with a handle that bores into the area tested and
brings up a sample of the soil from up to 15 feet deep. Soil samplers
can also be driven into the ground with the soil being collected in
liners that can be capped and sent directly to a laboratory for
analysis. For direct reading of contaminated soil, there are soil
tubes connected to a hand pump that draws an air sample into the tube
creating a reaction that discolors the tube and gives a qualitative
result.
The tools used in water sampling are bailers, coliwasas, dippers and
samplers.
- A bailer is an enclosed tube with a flowcheck device on
one end. When lowered to take a sample, the flowcheck device—typically
a ball—lets the sample in when lifted. The ball closes off the
end of the tube, capturing the sample.
- A coliwasa is an open tube made from either soda lime
glass, Teflon or other plastics. A coliwasa may have a manually
operated stopper for trapping samples, or the operator can put a
finger or other object over the end to create a vacuum to trap the
sample. The sample can then be released into a container to hold for
analysis. Coliwasas can be found in lengths up to 20 feet.
- Dippers have an extension handle with a beaker on the
end. These are used in areas that are accessible, such as streams,
lakes, tanks, industrial holding ponds, etc. The operator dips the
beaker into a stream and transfers the sample to a container.
- Samplers are similar to the dippers, but they have sample
bottles attached to the extension handle that can be enclosed and
sent for analysis. These bottles can be Teflon, plastic or glass.
The bottles come in different sampling sizes and the extension
handles can also be purchased in various lengths.
Sources for More Information
40 CFR 100–149.
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Please Note: The information contained in this
publication is intended for general information purposes only. This
publication is not a substitute for review of the applicable government
regulations and standards, and should not be construed as legal advice
or opinion. Readers with specific questions should refer to the cited
regulation or consult with an attorney.
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