Campbell Scientific Sentek EnviroSCAN Access Tube Installation Guide - Manual (Page 43)

Installing EnviroSCAN, EnviroSM ART & Diviner 2000 access tubes
© Sent ek Pt y Lt d Page 40
Hint:
If you encounter difficulties augering through rocky or stony soils with
the regular 61.0 mm (slurry auger), use the Open Centre Tungsten Tip
Auger 61.0 mm or Rock Breaker 54 mm Auger. The Open Centre
Tungsten Tip Auger is capable of breaking up and retrieving gravel of
up to thumbnail size. The 54 mm rock breaker will allow occasional
larger stones to be broken. The 54 mm rock breaker must be used with
the re-inforced T-Handle and auger extension rods.
If you still cannot auger a hole to the required depth, reposition the
auger in an alternative site, or use a motorized or mechanical auger to
drill the hole.
To drill the access tube hole using a motorized or mechanical auger
1. Select flight auger rods and attach a 61.0 mm tungsten tipped drill bit.
2. Attached the flight auger to a motor or drill rig assembly.
3. Use gloves, ear protectors and safety goggles to auger the hole to the required depth.
Notes on using a handheld motor auger:
Getting the correct hole size in various soils using a flighted auger requires an understanding of what is
happening while digging. In moist clay soils (or any soil which tends to adhere to the auger flight) the
procedure used will either produce too tight a hole or a correctly sized hole.
No hole should be dug by going straight down, without lifting at intervals to clear the soil from the hole, or an
undersized hole may result. The tendency for the soil to re-adhere to the wall of the hole as it moves up the
flight will cause the hole to be undersized from the cutter size, making digging forces greater and the effort
required to lift the auger out much harder.
To prevent this from happening, add a little water to the hole to “ease” the soil onto the flight each time the
auger motor starts to strain and the rotational force becomes hard to hold. Lifting the auger 150-200 mm
each time water is added will greatly assist the clearance of the soil up the flight. Stop the rotation for a few
seconds each time water is added to the hole to allow time for it to run down the flight to the digging point.
If the job is done correctly, the auger flight should be almost soil free when lifted from the hole. If not then
you may assume that too much soil has been retained on the flights and will tend to be forced back onto the
wall of the access hole. The walls of the hole should be moist and smooth, not rough.
Digging should be done by starting with a 0.5 or 1.0 metre auger flight. Add 0.5 metre extensions as
required.
Note: Sentek does not supply flight auger rods or mechanical augers, but can
refer customers to a suitable supplier if required.