Solinst is delighted to announce another installation of the New Narrow 3 Channel CMT (Continuous Multichannel Tubing) Multilevel System using bentonite cartridges. The cartridges are designed to seal the interval between monitoring zones and are ideal for direct push applications where the annulus between the CMT installation and the drilled hole is too small to accurately backfill a seal.
This new technology is of particular interest to Direct-Push Installers.
Direct-Push Well Technology has become increasingly accepted as it provides samples of comparable quality to conventional wells in a very cost-efficient manner. The main limitation to this type of technology has been the requirement by many regulatory groups to have a larger annular space in which to backfill seals. This problem can now be overcome with the development of filter packs and clay cartridges for the CMT System. A guidance document just released by the ITRC (The Interstate Technology & Regulatory Council), March 2006, discusses the advantages of using Direct Push methods and emphasizes that “Direct Push wells can be constructed with pre-installed filter packs and the well annulus can be sealed with a pre-installed bentonite sleeve”.
Atomic Energy of Canada Limited (AECL) selected the Narrow CMT 3 Channel bentonite cartridge system for an installation on their Chalk River facility. The system was installed to a depth of 80 ft (24 m) in bedrock with three cartridges situated above and below each port to seal the monitoring zone. A week after the installation, the system revealed vertical gradients and differing chemistry between the monitoring zones – proof of the effectiveness of the bentonite cartridge seals. Sampling is being performed using a peristaltic pump. Stephen Welch, a member of the AECL installation team indicated that the CMT construction and placement went off without a hitch and was “pretty slick”. They plan to continue with the installation of more systems this Summer.
In addition to providing bentonite cartridges for the Narrow CMT 3 Channel System, Solinst also offers other accessories. These include sand cartridges to cover the screen area of the monitoring port and flow-through wellhead plugs to facilitate vapor monitoring. The system is entirely constructed at surface and then lowered into the borehole, ensuring accurate seal placement. The 7 Channel CMT system is also available for applications requiring a larger number of monitoring zones or installation in larger diameter boreholes using standard backfilling techniques.
ITRC (Interstate Technology & Regulatory Council). 2006. The Use of Direct-push Well Technology for Long-term Environmental Monitoring in Groundwater Investigations. SCM-2. Washington, D.C.: Interstate Technology and Regulatory Council, Sampling Characterization and Monitoring Team.
Acknowledgement: Solinst would like to thank Stephen Welch of AECL for providing feedback and technical details on the CMT installation.
Note: Solinst now sells a newer version of this bentonite cartridge, the spring cartridge, which uses bentonite pellets.