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Soil sampling

During drilling operations the following activities will be undertaken:

  • Head-space measurements. Field screening of soil samples from all locations at approximate 0,5-1 m intervals or as determined by field observations. Presence of any visual or olfactory evidence of contamination should be detected. Moreover, a hand-held PID (Photo Ionization Detector) can be used for rapid analysis of samples in field. These samples may be packed in rilsan bags, closed tightly and kept for a period of 10-15 minutes before measurement at temperatures between 15-23 ºC.
  • Soil sampling. Soil samples should be collected based on head-space measurements and organoletpic characteristics, avoiding overheated zones and discarding coarse materials.

One or two soil samples may be collected at most impacted depths, which will be estimated based on previous head space measurements and organoleptic characteristics. To prevent cross contamination, the outer couple of centimeters must be removed using a clean trowel/scraper. The soil sample is taken using a trowel/scraper/hollow sampler and put directly into the sample container. Normally, 250 g of soil are used for chemical analysis, while approximately 200-300 g are used for geological characterization. Afterwards, the laboratory will extract test portions of the incoming sample in accordance with the amount needed for analysis.

One or two soil samples may be collected at most impacted depths, which will be estimated based on previous head space measurements and organoleptic characteristics.

To prevent cross contamination, the outer couple of centimeters must be removed using a clean trowel/scraper. The soil sample is taken using a trowel/scraper/hollow sampler and put directly into the sample container. Normally, 250 g of soil are used for chemical analysis, while approximately 200-300 g are used for geological characterization. Afterwards, the laboratory will extract test portions of the incoming sample in accordance with the amount needed for analysis.

In order to ensure a representative sample is collected, a series of quality procedures will be followed:

  • Immediate closing and labeling of samples, writing down the sample code, time and date, the field specialist initials, and the analyses to be performed.
  • Disposable (e.g., gloves) or decontaminated sampling devices will be used.
  • Containers provided by the laboratory will be used.
  • In case of collection of samples clearly impacted, careful decontamination of used devices will be necessary.
  • Samples will be stored in refrigerated containers or thermo insulated boxes, far from areas with air-dispersed contamination.
  • Collected samples, after labeling and Chain of Custody editing, will be put in 4° C     containers and sent to the laboratory for the analyses normally in 24-48 hours. Nevertheless, time length before sending the samples to the laboratory might be specified by the laboratory depending on the characteristics of these samples.
  • A Chain of Custody, which will include for each sample the same information reported on its label, will be completed.


Soil samples should be also correctly classified, for example according to the Unified Soil Classification System (USCS) and the following information should be recorded for different depths on a boring log:

  • Soil type
  • Consistency of fine grain soils
  • Colour
  • Moisture content
  • Grain size distribution
  • Presence of groundwater
  • Presence or absence of contamination
  • Soil classification symbol
  • Textural changes
  • Other relevant information


Moreover, during sampling preparation the following additional sampling information will be recorded:

  • Sample identification numbers and explanatory code
  • Sample location and description
  • Sampler’s name(s)
  • Date and time of sample collection
  • Designation of organic compounds
  • Type of sample (soil, sediment or water)
  • Type of sampling equipment used
  • Field instrument reading, if applicable
  • Field observations and details related to analysis or integrity of samples (e.g., weather conditions, noticeable odors, colors, etc.)
  • Sample preservation
  • Name of recipient laboratory


Finally, photographs will be taken at the sampling locations and at surrounding areas.  The photos will verify information entered in a field logbook. Each photo taken will be written in the logbook with the approximate time, date, and location.