Sampling is usually the second step in the Environmental Assessment
process. The sampling and analysis focus on confirming whether any
contamination exists, locating the contamination, and characterizing
the nature and extent of contamination. Sampling may include soil,
groundwater, surface water, sediment, building materials, waste
products and debris. The purpose of this step is to develop a reasonably
comprehensive understanding of what contaminants are present, where
they are located, and at what levels they are found.
Sampling is accomplished using field analytical technologies, which
measure chemical concentrations on-site, and by collecting samples
from the site, and analyzing them at an environmental laboratory.
In addition, a variety of other techniques are normally used to
evaluate physical characteristics of the site that may be relevant,
such as the direction of groundwater flow, surface slope, and the
presence of buried materials. Once data is collected, the site can
be evaluated based on the State and/or Federal cleanup requirements.
Refer to Regulations for more information.
The type of sampling during an Environmental Assessment is dependent
on the following:
- Suspected type of contamination
- Suspected source of contamination
- Expected depth of contamination
- Soil/geological conditions
- Groundwater depth
Samples are obtained by a variety of methods such as:
- Surface grab sample
- Shallow hand auger sample
- Backhoe sampling
- Soil gas sampling
- Direct push sampling-use of Geoprobe in ground to obtain soil
- Groundwater monitoring-installation of well for periodic monitoring
Sampling takes both time and money. There are two simple sampling
principles: there should be a clear plan for how the sampling data
will be used; and data are useless if not collected properly including
the collection, preservation and analysis.
There are six questions one should ask prior to sampling:
- What types of samples are needed?
- Where should samples be collected?
- When should samples be collected?
- How many samples are needed?
- What types of quality control (QC) samples are needed?
- How many QC samples are needed?
A sample plan is useful for planning and executing sampling procedures.
The EPA provides a sample plan outline that can be used. Example
A sample protocol are written descriptions of detailed procedures
to be followed in the collection, packaging, labeling, preservation,
transportation, storage and documentation. Example Sample Protocol.
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