We make casing from lightweight steel, or aluminium with brass threads in sizes 50mm, 62mm, 75mm, and 90mm OD and either 1.0 or 1.5-meter lengths.
Threads are either “fine” parallel pipe thread or “coarse” square acme threads.
Options: Length; Materials made from; Thread type.
Item Code CAS
The casing needs to be installed over the full depth of the hole and can be done using either of two methods.
One method is to install the casing from the beginning of the hole and to drill inside the casing using a smaller diameter auger. This is slower because of the effort required advancing the casing in hard ground and unless the auger takes out full cross-section inside the casing, contamination of the sample can occur.
Also, there is more surface friction on the outside when it comes to removing the casing.
The second and more popular method is to drill the hole initially down to the water table using an auger slightly larger than the casing OD and then install the casing.
This reduces friction on the outside and allows the casing to inserted much more easily. When adding lengths of the casing, use the Strap Wrench to tighten the joints while holding the lower section with the Casing Clamp.
When the casing reaches the bottom of the auger hole, fit a Casing Collar to the top thread to protect it. Insert an auger and remove any fall-in or surplus and discard it.
When the sample proves two wet to extract using a normal auger,
a Sludger or Bailer is used.
By pumping the sludger up and down in short vigorous or long rhythmic movements using either a rope type of the extention rod type sludger, while adding downward weight(standing on or hang sandbags on the Casing Clamp) onto the casing via the Casing Clamp, a sample will fill the sludger and the casing will penetrate.
Care needs to be taken to ensure the sample is not taken from below the end of the casing and to watch for “welling up” caused by the water pressure pushing materials into the end of the casing.
It helps to withdraw the sludger slowly so as to reduce the suction effect, and to keep the inside of the casing topped up with the water to balance the pressure.
Depths of up to 30 meters below the water table have been achieved but on average, 8 meters.
Other hints are:
- Never leave the equipment in the hole unnecessarily as it may get stuck.
- If gravel or stones are encountered, chop them up using the Star Drill or Chisel and remove the pieces with the stone Catcher and the Slide Hammer to force-fill it.
- Remove the casing as soon as possible or it will need mechanical extraction. Using a jack (the high lift jacks used by the 4WD’ers are good) under the casing clamp or a tripod (we make them) connected to the Casing Collar helps remove the difficult casing.
- Regularly rotate the casing clockwise only, using the Casing Clamp to help penetration or removal. Do not turn more than half a turn anticlockwise or the joints may undo.
Do not use pipe wrenches (stilsons) on the casing as it damages the lightweight walls and the threads may go out-of-round. Our Strap Wrenches are an infinitely better choice by far.