ASTM D6640-21

5.1?Often during environmental investigations, soils are analyzed after being collected from the surface, the vadose zone (Terminology D653), and sometimes from below the groundwater table to identify and quantify the presence of a chemical contaminant. A contaminant is a substance that is typically hazardous and either is not normally present or that occurs naturally but is of an uncharacteristically high concentration (Guide D4687). A three-dimensional spatial array of samples can often provide information as to the source and route(s) of migration of the contaminant. The resultant information is used to direct remedial and corrective actions or can be used for monitoring purposes. Obtaining a soil sample with a core barrel sampler involves driving this device into the ground and then retrieving it for sample processing. Several methods for advancing a core barrel are generally acceptable (for example, Test Method D1586; Practices D1587, D3550, and D6151; Guides D5784, D5875, D5876, D6169, and D6282). Drilling methods that use drilling fluids (liquids or air) should be avoided because they are more susceptible to cross-contamination (Guide D6286) (see 6.1.6).

5.2?If samples are to be collected for the determination of per- and poly-fluorinated alkyl substances (PFAS), all sampling equipment should be made of fluorine-free materials. Other considerations for PFAS sampling may exist but are beyond the scope of this standard.

1.1?This practice covers procedures for obtaining soils from core barrel samplers for chemical and physical analysis, with an emphasis on the collection and handling procedures that maintain the representativeness of the chemical contaminants of concern. Core barrel samplers are initially empty (hollow) until they are pushed into the ground to collect and retrieve a cylindrical soil sample with minimal disturbance. The selection of equipment and the sample handling procedures are dependent on the soil properties, the depth of sampling, and the general properties of the chemical contaminants of concern, that is, volatile organic compounds, semi-volatile organic compounds, and inorganic constituents. The sampling procedures described are designed to maintain representative concentrations of the contaminants regardless of their physical state(s), that is, solid, liquid, or gas.

1.2?This practice covers soil samplers used in Guide D6169 on soils and rock sampling and included in Guide D6232 for waste sampling. Guide D6169 provides additional information on samplers and procedures that will preserve representative contaminate concentrations. Guide D6282 is on direct-push soil samplers that are most frequently used for environmental work. Guide D4547 addresses special sampling of soils for volatile compounds. This standard does not include sediment samplers in Guide D4823, but the same principles may apply to handling of those cores. Guide D4700 includes information on shallow manual push soil samplers.

1.3?Five general types of core barrel samplers are discussed in this practice: split-barrel, soil corer, ring-lined barrel, thin-walled tube, and solid-barrel samplers.

1.4?This document does not cover all the core barrel devices that are available for the collection of soil samples.

1.5?The procedures described may or may not be applicable to handling of samples for assessing certain geotechnical properties, for example, soil porosity.

1.6?UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.

1.7?This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.8?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.