GENERAL FIELD
SAMPLING GUIDELINES
SOP#: 2001
DATE: 08/11/94
REV. #: 0.0
1.0 SCOPE AND APPLICATION
The purpose of this Standard Operating Procedure
(SOP) is to provide general field sampling guidelines
that will assist REAC personnel in choosing sampling
strategies, location, and frequency for proper
assessment of site characteristics. This SOP is
applicable to all field activities that involve sampling.
These are standard (i.e., typically applicable)
operating procedures which may be varied or changed
as required, dependent on site conditions, equipment
limitations or limitations imposed by the procedure. In
all instances, the ultimate procedures employed should
be documented and associated with the final report.
Mention of trade names or commercial products does
not constitute U.S. EPA endorsement or
recommendation for use.
2.0 METHOD SUMMARY
Sampling is the selection of a representative portion of
a larger population, universe, or body. Through
examination of a sample, the characteristics of the
larger body from which the sample was drawn can be
inferred. In this manner, sampling can be a valuable
tool for determining the presence, type, and extent of
contamination by hazardous substances in the
environment.
The primary objective of all sampling activities is to
characterize a hazardous waste site accurately so that
its impact on human health and the environment can
be properly evaluated. It is only through sampling and
analysis that site hazards can be measured and the job
of cleanup and restoration can be accomplished
effectively with minimal risk. The sampling itself
must be conducted so that every sample collected
retains its original physical form and chemical
composition. In this way, sample integrity is insured,
quality assurance standards are maintained, and the
sample can accurately represent the larger body of
material under investigation.
The extent to which valid inferences can be drawn
from a sample depends on the degree to which the
sampling effort conforms to the project's objectives.
For example, as few as one sample may produce
adequate, technically valid data to address the
project's objectives. Meeting the project's objectives
requires thorough planning of sampling activities, and
implementation of the most appropriate sampling and
analytical procedures. These issues will be discussed
in this procedure.
3.0 SAMPLE PRESERVATION,
CONTAINERS, HANDLING,
AND STORAGE
The amount of sample to be collected, and the proper
sample container type (i.e., glass, plastic), chemical
preservation, and storage requirements are dependent
on the matrix being sampled and the parameter(s) of
interest. Sample preservation, containers, handling,
and storage for air and waste samples are discussed in
the specific SOPs for air and waste sampling
techniques.
4.0 INTERFERENCES AND
POTENTIAL PROBLEMS
The nature of the object or materials being sampled
may be a potential problem to the sampler. If a
material is homogeneous, it will generally have a
uniform composition throughout. In this case, any
sample increment can be considered representative of
the material. On the other hand, heterogeneous
samples present problems to the sampler because of
changes in the material over distance, both laterally
and vertically.
Samples of hazardous materials may pose a safety
threat to both field and laboratory personnel. Proper
health and safety precautions should be implemented
when handling this type of sample.
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Environmental conditions, weather conditions, or
non-target chemicals may cause problems and/or
interferences when performing sampling activities or
when sampling for a specific parameter. Refer to the
specific SOPs for sampling techniques.
5.0 EQUIPMENT/APPARATUS
The equipment/apparatus required to collect samples
must be determined on a site specific basis. Due to the
wide variety of sampling equipment available, refer to
the specific SOPs for sampling techniques which
include lists of the equipment/apparatus required for
sampling.
6.0 REAGENTS
Reagents may be utilized for preservation of samples
and for decontamination of sampling equipment. The
preservatives required are specified by the analysis to
be performed. Decontamination solutions are
specified in ERT SOP #2006, Sampling Equipment
Decontamination.
7.0 PROCEDURE
7.1 Types of Samples
In relation to the media to be sampled, two basic types
of samples can be considered: the environmental
sample and the hazardous sample.
Environmental samples are those collected from
streams, ponds, lakes, wells, and are off-site samples
that are not expected to be contaminated with
hazardous materials. They usually do not require the
special handling procedures typically used for
concentrated wastes. However, in certain instances,
environmental samples can contain elevated
concentrations of pollutants and in such cases would
have to be handled as hazardous samples.
Hazardous or concentrated samples are those collected
from drums, tanks, lagoons, pits, waste piles, fresh
spills, or areas previously identified as contaminated,
and require special handling procedures because of
their potential toxicity or hazard. These samples can
be further subdivided based on their degree of hazard;
however, care should be taken when handling and
shipping any wastes believed to be concentrated
regardless of the degree.
The importance of making the distinction between
environmental and hazardous samples is two-fold:
(1) Personnel safety requirements: Any sample
thought to contain enough hazardous
materials to pose a safely threat should be
designated as hazardous and handled in a
manner which ensures the safety of both field
and laboratory personnel.
(2) Transportation requirements: Hazardous
samples must be packaged, labeled, and
shipped according to the International Air
Transport Association (IATA) Dangerous
Goods Regulations or Department of
Transportation (DOT) regulations and U.S.
EPA guidelines.
7.2 Sample Collection Techniques
In general, two basic types of sample collection
techniques are recognized, both of which can be used
for either environmental or hazardous samples.
Grab Samples
A grab sample is defined as a discrete aliquot
representative of a specific location at a given point in
time. The sample is collected all at once at one
particular point in the sample medium. The
representativeness of such samples is defined by the
nature of the materials being sampled. In general, as
sources vary over time and distance, the
representativeness of grab samples will decrease.
Composite Samples
Composites are nondiscrete samples composed of
more than one specific aliquot collected at various
sampling locations and/or different points in time.
Analysis of this type of sample produces an average
value and can in certain instances be used as an
alternative to analyzing a number of individual grab
samples and calculating an average value. It should
be noted, however, that compositing can mask
problems by diluting isolated concentrations of some
hazardous compounds below detection limits.
Compositing is often used for environmental samples
and may be used for hazardous samples under certain
conditions. For example, compositing of hazardous
waste is often performed after compatibility tests have
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been completed to determine an average value over a
number of different locations (group of drums). This
procedure generates data that can be useful by
providing an average concentration within a number
of units, can serve to keep analytical costs down, and
can provide information useful to transporters and
waste disposal operations.
For sampling situations involving hazardous wastes,
grab sampling techniques are generally preferred
because grab sampling minimizes the amount of time
sampling personnel must be in contact with the
wastes, reduces risks associated with compositing
unknowns, and eliminates chemical changes that
might occur due to compositing.
7.3 Types of Sampling Strategies
The number of samples that should be collected and
analyzed depends on the objective of the investigation.
There are three basic sampling strategies: random,
systematic, and judgmental sampling.
Random sampling involves collection of samples in a
nonsystematic fashion from the entire site or a specific
portion of a site. Systematic sampling involves
collection of samples based on a grid or a pattern
which has been previously established. When
judgmental sampling is performed, samples are
collected only from the portion(s) of the site most
likely to be contaminated. Often, a combination of
these strategies is the best approach depending on the
type of the suspected/known contamination, the
uniformity and size of the site, the level/type of
information desired, etc.
7.4 QA Work Plans (QAWP)
A QAWP is required when it becomes evident that a
field investigation is necessary. It should be initiated
in conjunction with, or immediately following,
notification of the field investigation. This plan should
be clear and concise and should detail the following
basic components, with regard to sampling activities:
• Objective and purpose of the investigation.
• Basis upon which data will be evaluated.
• Information known about the site including
location, type and size of the facility, and
length of operations/abandonment.
• Type and volume of contaminated material,
contaminants of concern (including
concentration), and basis of the
information/data.
• Technical approach including media/matrix
to be sampled, sampling equipment to be
used, sample equipment decontamination (if
necessary), sampling design and rationale,
and SOPs or description of the procedure to
be implemented.
• Project management and reporting, schedule,
project organization and responsibilities,
manpower and cost projections, and required
deliverables.
• QA objectives and protocols including tables
summarizing field sampling and QA/QC
analysis and objectives.
Note that this list of QAWP components is not all-
inclusive and that additional elements may be added
or altered depending on the specific requirements of
the field investigation. It should also be recognized
that although a detailed QAWP is quite important, it
may be impractical in some instances. Emergency
responses and accidental spills are prime examples of
such instances where time might prohibit the
development of site-specific QAWPs prior to field
activities. In such cases, investigators would have to
rely on general guidelines and personal judgment, and
the sampling or response plans might simply be a
strategy based on preliminary information and
finalized on site. In any event, a plan of action should
be developed, no matter how concise or informal, to
aid investigators in maintaining a logical and
consistent order to the implementation of their task.
7.5 Legal Implications
The data derived from sampling activities are often
introduced as critical evidence during litigation of a
hazardous waste site cleanup. Legal issues in which
sampling data are important may include cleanup cost
recovery, identification of pollution sources and
responsible parties, and technical validation of
remedial design methodologies. Because of the
potential for involvement in legal actions, strict
adherence to technical and administrative SOPs is
essential during both the development and
implementation of sampling activities.
Technically valid sampling begins with thorough
planning and continues through the sample collection
and analytical procedures. Administrative
requirements involve thorough, accurate
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documentation of all sampling activities. 10.0 DATA VALIDATION
Documentation requirements include maintenance of
a chain of custody, as well as accurate records of field Refer to the specific SOPs for data validation
activities and analytical instructions. Failure to activities that are associated with sampling
observe these procedures fully and consistently may techniques
result in data that are questionable, invalid and
non-defensible in court, and the consequent loss of 110 HEALTH AND SAFETY
enforcement proceedings.
When working with potentially hazardous materials,
8.0 CALCULATIONS follow U.S. EPA, OSHA, and corporate health and
safely procedures.
Refer to the specific SOPs for any calculations which
are associated with sampling techniques.
9.0 QUALITY ASSURANCE/
QUALITY CONTROL
Refer to the specific SOPs for the type and frequency
of QA/QC samples to be analyzed, the acceptance
criteria for the QA/QC samples, and any other QA/QC
activities which are associated with sampling
techniques.
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