Planning the cable path
OmniTrax Product Guide Page 35
Using geotextile fabric in sensor cable installations
Senstar recommends using geotextile fabric and a stone dust (or sand) bedding for installations in
coarse rock and heavy clay. A stone dust or sand bedding wrapped in geotextile fabric protects the
sensor cables from rocks and helps protect against potential damage due to landscaping and
maintenance activities. The geotextile fabric prevents the protective bedding from erosion, thus
prolonging the installation lifetime. By maintaining a uniform installation environment around the
cables, the sand and geotextile fabric helps to maintain consistent detection sensitivity along the
full cable length.
Above ground berm installation using geotextile fabric
Berm installation is used when it is necessary to elevate the zone while providing protection from
erosion, for example, when sensor cables must pass over exposed bedrock or water saturated
soil. The geotextile fabric retains the sand around and between the sensor cables. There are three
methods for berm installations:
• Enclosing both sensor cables in a wide, sloped sand bedding, which is wrapped in geotextile
fabric and then covered with clear crushed stone.
• Enclosing both sensor cables in a narrow, rounded sand bedding, which is wrapped in
geotextile fabric and then covered with clear crushed stone.
• Enclosing each sensor cable in a narrow, rounded sand bedding, which is wrapped in
geotextile fabric and then covered with clear crushed stone.
Landfill
Avoid laying the cables in areas that are filled with debris containing large metal objects. Large
metal objects usually have electrical properties that can affect the detection field. Decaying metal
objects can cause nuisance alarms, because their electrical properties can alter sporadically as
ground conditions change. The metal objects can also cause variations in sensitivity and detection
field size. If the installation area appears to have been filled with debris, use a metal detector to
check for metal material. Locate and remove any significant findings where possible. If it is
suspected that the soil has been contaminated by chemicals, a soil analysis for electrical and
chemical properties should be done. If the installation area is filled with slag, or processed metal
ores, take some soil samples and examine them for metal material content. Check the samples
with a magnet to determine if magnetic properties exist. Other objects located below the ground
and near the surface may cause nuisance alarms. These objects should be identified and located
on the site survey.
Grade changes
The surface grade along the proposed cable path must not change by more than 30° within a 4 m
(13 ft.) span. If there are any areas along the cable path where the slope exceeds 30° within 4 m,
fill or level the terrain to meet the maximum allowable slope specification.
Note If significant metal content is suspected or found, or if there are
chemical contaminants in the soil, contact Senstar Customer Service for
applications advice.
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