Planning the cable path
Page 32 OmniTrax Product Guide
Make notes about all installation mediums (concrete, reinforced concrete, asphalt, gravel, different
types of soil, etc.) located along the proposed cable route. Include the locations of the boundaries
between the different mediums. The composition of the soil (conductivity) and the location of any
vegetation should also be recorded. If a sensor cable set will be installed in more than one burial
medium, try to avoid situations where one cable set is buried in both heavy soil and light soil.
If clear crushed stone is used as a topping, Senstar recommends stone with a maximum size of
19 mm (3/4 in.). Stone dust used to surround and protect the sensor cable should be fine
aggregate (passes 4.75 mm No. 4 sieve).
Soil types
Soil types can vary from dry, sandy soil to heavy clay. Sand is considered a light soil because it
has low conductivity and a low dielectric constant. Clay is considered a heavy soil as it has
opposite characteristics to sand. For extremely light soil, detection field containment can be an
issue. For heavy or “lossy” soil, detection sensitivity can be an issue.
Light soil extreme
The light soil extreme can be assessed visually where the site is loose sand or dry granular
material, without moisture, extending to the approximate burial depth of the cable. A further
indicator is that the installation area is devoid of vegetation, as few plants grow under such
conditions. If any vegetation is present, it is sparse and loosely rooted. In some cases, the soil is
stratified with a sandy layer around the cable, and a more dense soil layer below. If the cables
burial depth is more than 5 cm (2 in.) above the dense layer, it is considered light soil. However, if
the cables are less than 5 cm above the dense layer, then this type of stratified media behaves
more like a heavy soil.
Heavy soil extreme
Heavy clay soil is a layer of pure clay with an extremely high conductivity (> 200 mS/m). When dry,
the surface of a heavy clay soil will be very hard and cracked, and any dried excavated lumps will
be very hard. When wet, this soil will be workable like modeling clay. A sample can be rolled into a
cylinder between your palms, about 1 cm (0.4 in.) in diameter and the length of your palm, without
falling apart. Included in this class of soils are naturally wet soils, such as those found in saturated,
or coastal marsh areas. Heavy clay soil requires variations in the installation techniques.
Moderate clay soil is a mixture of standard organic soil types with a higher than normal clay
content. The surface of a moderate clay soil type will be very hard when it is dry. Excavation with a
shovel is quite difficult. When moderate clay soil is wet, it will be workable. A sample can be
squeezed between the palms without breaking up. Moderate clay soil also requires variations in
the installation techniques.
Note Micro-trenching is a valid installation option for soil and asphalt, and can
be used provided that the trench depths and backfill requirements are
maintained. Micro-trenching cannot be used in heavy clay soil.
Note Extreme soil types such as very dry sand and moderate to heavy clay
require variations in installation methods and burial depths. Contact
Senstar Customer Service for additional information.
Note Installation in clay soils, requires the use of a dual cable system (OC2
or SC2, not SC1). See application note 5 (A4DA0509) for details.
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