Campbell Scientific Sentek EnviroSCAN Access Tube Installation Guide - Manual (Page 38)

Installing EnviroSCAN, EnviroSM ART & Diviner 2000 access tubes
© Sent ek Pt y Lt d Page 35
Slurry Installation Method
What are the different slurry methods?
The slurry installation methods are techniques used in soils with a high stone and gravel content. Stony soils
are hard to auger and do not break up evenly. Large air pockets form easily when installing access tubes in
these soils, causing unreliable readings.
Note:
The slurry methods are suggested for:
• Where the site soil has been tested and found to be high in stone and gravel content
• In access tube installations deeper than 2.5 – 3 m.
Warning:
Slurry installations are not recommended in sandy soils.
A slightly oversized hole is drilled and party filled with slurry. The slurry is a special mud mixture of kaolinite
and cement that is poured into the augered hole and fills the spaces where air would normally gather. The
access tube is pushed through the slurry and air bubbles move up through the slurry and are released. As
the slurry dries, its moisture content balances with the moisture content of the surrounding soils.
Note: The equilibrium with the surrounding soil may not be 100%, however the
sphere of influence of the sensor penetrates the 5-10 mm slurry and measures the
soil water content of the surrounding soil.
Although you are not measuring the pure undisturbed soil with this installation method, Sentek experience
has shown that you can achieve good scientific study outcomes and commercial benefits using this method.
Warning:
If you require absolute data, Sentek sensors need to be calibrated with the dried
slurry in place, as described in the Sentek Calibration Manual.
Two drilling methods are used for slurry installations:
• Manual slurry installation method – where a slightly oversized hole is drilled into very stony and
gravelly soils using a hand auger
• Machine slurry installation method – where a slightly oversized hole is drilled into very stony
and gravelly soils using a motorized auger.
The access tube installation is the same for both methods, which are described in detail below.
Sentek has developed a set of installation tools specifically for manual slurry installations (Slurry Access
Tube Installation Kit).
An installation requires:
• Sentek access tube items
• Slurry Access Tube Installation Toolkit
Read through the installation method to identify the tools you will need and understand their use. Ensure
that you have the tools you require before proceeding to the installation site.