Commonly just called “The 420”, this drill is the smallest drill produced by GeoProbe and the smallest of our three direct push machines. The drill is used at similar sites where the Big Beaver is also a viable option, though it has some notable differences in characteristics. Like the Big Beaver, the drill operates through the use of a remote hydraulic power unit, permitting fumeless indoor drilling. Unlike the Big Beaver, this machine uses direct push tooling and does not do split spoon sampling, thereby making it unsuitable for most geotechnical investigations.
This is our least used drill, as many of the things it can do, the Big Beaver or the MiniProbe can do better. That being said, this machine is the premier drill for getting into basements with only 7 feet of headroom for environmental sampling as it is smaller, lighter, and more nimble than the Big Beaver, but substantially more powerful than hand held rapid percussion drills like the Pionjar. For “nice” areas like inside small stores, offices, and strip plazas, the machine is cleaner than the Big Beaver as there is less ancillary equipment and no auger cuttings to dirty the drilling area.
Using 2ft lengths of dual tube direct push tooling (DT22), the machine affords some of the benefits of larger direct push drills and can even be used to install monitoring wells in the cased hole or in the open hole after removing the down-hole tooling.