When using Cartridges, there are Sand Cartridges, and Bentonite Spring Cartridges, where the Cartridge is filled in the field with 3/8" (9.5 mm) diameter bentonite pellets. These Cartridges, shown in Figure 25, can be used in series or in combination with each other.
Installations using Cartridges are done in 3.25" OD direct-push and NQ boreholes.
Figure 25 - CMT Multilevel System Sand Bentonite Cartridges
Bentonite Spring Cartridges are used for low pressure seals (<5psi) in non-caving boreholes < 4.0" dia. Allow 2 to 3 days to seal.
The use of Sand and Bentonite Cartridges allow the CMT Multilevel System to be installed in 3.25" (82.5 mm) (2.6" ID (66 mm)) diameter "Direct Push" casing fitted with a knock-out cutting shoe. Bentonite and Sand Cartridges are 2.5" (64 mm) in diameter and are a nominal 12" (305 mm) length. The Cartridges slide onto the CMT and a Gear Clamp is torqued in place to stop each Cartridge from moving. One 3.5" (89 mm) diameter Separator Disk is below each Cartridge to help minimize the potential for vertical sediment movement. Spacers are used between each Cartridge and Separator Disk. Thus, the entire CMT Assembly is built right at the borehole, and then inserted hand-over-hand to the desired depth. Figure 26 shows all of the above described components required for Cartridge installation.
If using 3.25" diameter "Direct-Push" casing, ensure you are using a knock-out cutting shoe for the installation.
Figure 26 - Components and Tools Needed for CMT Multilevel System Sand and Bentonite Cartridge Installation