Sampling

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 sample
  • Groundwater monitoring-installation of well for periodic monitoring

Sampling Basics

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.

Sampling Strategies

There are six questions one should ask prior to sampling:

  1. What types of samples are needed?
  2. Where should samples be collected?
  3. When should samples be collected?
  4. How many samples are needed?
  5. What types of quality control (QC) samples are needed?
  6. How many QC samples are needed?

Examples

A sample plan is useful for planning and executing sampling procedures. The EPA provides a sample plan outline that can be used. Example Sample Plan.

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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