DT60 Soil Sampling System Overview
The DT60 soil sampling system is the largest dual tube system from Geoprobe®. It utilizes a 6 inch outer diameter percussion driven casing that remains in place during sampling. Four inch diameter soil cores are retrieved from each sampling interval with an inner string of two and a quarter inch rods. This yields 3.6 times more soil volume than DT325 and 6 times more soil volume than MC5. Unlike most other sampling systems, the DT60 uses a patented split sample sheath which gives the user the option of running without a liner.
In addition to soil sampling, the DT60 system can also be used to install 2 inch monitoring wells without driving a second tool string. That means you can collect continuous soil cores and install a 2 inch prepack or conventional well within a 6 inch borehole – all in one shot, saving time and money! All of this is done safely with no entanglement hazards from rotating parts or tools.
Assembly begins with a DT60 cutting shoe installed on the box end of of a 6 inch probe rod that is 5 feet in length. This is followed by a 6 inch probe rod that is 12 inches in length.
Next we will assembly our sheath components. First we’ll start with a holding ring, core catcher, and retainer. This will be connected to the split sheath. On the opposite end of the sheath we have two components - the split sheath drive head and the DT60 centering drive cap. We’ll start with the drive head followed by the DT 60 2.25 in. centering drive cap.
With the sheath assembly completed, we can now install it in the six inch probe rod assembly. With the sheath assembly installed, we’ll add the centering drive cap.
To begin sampling, the leading outer casing and sample sheath are driven to a depth of five feet. The drive cap and centering drive cap are removed and the spring assisted swivel pull cap is attached to the top of the DT60 split sheath drive head. With the winch attached, the sample assembly is pulled to the surface.
The sample assembly is disassembled by removing the drive head, holding ring, core catcher and retainer, revealing the sample from one to five feet. After removing the sample, the sheath is reassembled with the optional liner, holding ring, core catcher, retainer, and drive head. The winch is used to lower the sample assembly back down hole. A two and a quarter inch center rod is attached to the top of the split sheath drive head.
An additional 60 inch outer casing is attached to the top of the tool string, followed by the centering drive cap and outer casing drive cap. The whole string is driven to a depth of 10 feet. Using a combination of the spring assisted swivel pull cap, winchs, and rod clamp, the sample sheath assembly is brought to the surface. The sample assembly is disassembled, revealing the sample from six to ten feet. This process is repeated for each sampling interval.
The DT60 sampling system is the largest dual tube system from Geoprobe®. It is an efficient system for collecting 4 inch soil samples and installing 2 inch prepacks with your 32 Series and 8040DT rigs.
For more information, visit our website or call us at 785-825-1842.