most cases, the Agency discourages the sole use of the driven well construction method for
the purpose of installing monitoring wells. This is primarily because of the inability to
collect representative samples of the materials that are penetrated during well installation, and
of the inability to seal the well properly unless an outer casing is driven first. However, if
samplers can be driven in advance of the casing to allow subsurface sample collection, the
driven well method may be a viable well installation option.
Jet Percussion
The jet percussion drilling method uses a wedge shaped drill bit attached to the end of
the drill pipe. Water is forced under pressure down the drill pipe and is discharged through
ports on the sides of the drill bit. The bit is lifted and dropped while rotating. The water is
forced up the annular space between the drill pipe and the borehole wall, carrying cuttings to
the surface. The method is limited to unconsolidated or soft consolidated formations. The
disadvantages of this method include the inability to collect representative samples of ground 
water, soil, or unconsolidated deposits during drilling and the potential for disturbing the
Decontamination of Drilling Equipment
All drilling equipment that will encounter formation materials (e.g., augers, samplers,
tremie pipes) should at a minimum be decontaminated between boreholes, and in the case of
samplers, between samples. When cross contamination between zones within a single
borehole is a concern, equipment should be decontaminated more frequently. Aller et al.
(1989) provide a comprehensive discussion of decontamination of drilling and formation 
sampling equipment.
The types of drilling and sampling equipment that should be decontaminated (Aller et
al., 1989) include:
Drill bits;
Auger sections;
Drill string tools;
Drill rods;
Sampling equipment (e.g., split spoons);
Bailers used for well development or for the removal of fluids from the well;
Tremie pipes;
November 1992
6 14






 Home | About Us | Network | Services | Support | FAQ | Control Panel | Order Online | Sitemap | Contact

quality web hosting


Our partners: PHP: Hypertext Preprocessor Cheap Web Hosting JSP Web Hosting Ontario Web Hosting  Jsp Web Hosting

Cheapest Web Hosting Java Hosting Cheapest Hosting Business web hosting division of Vision Web Hosting Inc.. All rights reserved