Subsurface Drilling

Subsurface drilling for groundwater remedial investigations uses much of the same technology as conventional geotechnical exploration but with some significant differences. Geotechnical exploration requires the collection of an intact physical specimen which can be tested for geo-technical properties. In comparison, groundwater remedial investigations require that the specimen also be representative of existing conditions and valid for chemical analysis. Therefore, the selection of drilling methods and sampling protocols in a groundwater remedial investigation is more restrictive and should be based upon site-specific conditions and the type of testing to be done.

The criteria used in the selection of a drilling method include the type of geological formation, depth of drilling, depth of screen setting, types of pollutants expected, accessibility to the site, and availability of drilling equipment. The following section briefly describes the drilling methods used in groundwater remedial investigations.

Pilot assembly components

Pilot Bit

Rod to cap adapter

Auger connector

Hollow stem auger section

- Auger connector

- Auger head Replaceable carbide insert auger tooth

Rod to cap adapter

Auger connector

Hollow stem auger section

- Auger connector

- Auger head Replaceable carbide insert auger tooth

FIG. 9.15.1 Hollow-stem auger system. (Reprinted from U.S. Environmental Protection Agency, 1993, Subsurface characterization and monitoring techniques, a desk reference guide, Vol. 1, USEPA/625/R-93/003a [May] U.S. EPA.)

Pilot Bit

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