Preparation of trenches
OmniTrax Product Guide Page 111
• water supply and hose
• hammer and cold chisel
• closed cell foam polyethylene backer rods - 2 rows of backer rods per slot
(use backer rods that are app. 3 mm (1/8 in.) wider than the slots)
• PVC pipe 1 - 7 m (3.3 - 23 ft.) long x 2 cm (¾ in.) inside diameter (required only at media
transitions, e.g., concrete to soil)
• joint sealant (to seal the sensor cables in the slot)
chemical sealant - minimum 20 liters per 100 m (5.3 US gallons per 328 ft.) of sensor cable
tape sealant - length of slot + 5%
For additional information, see Supplier’s information
on page 240.
Slot dimensions
Cutting the basic slot
1. Mark the cable path on the ground.
2. Using a concrete saw, cut the slots along the marked cable path.
3. At slot corners, use a hammer and cold chisel to remove any sharp edges that could cut into
the cable jacket.
4. Remove any debris from the slots, cracks and joints, and from an area 30 cm (12 in.) on both
sides of the slots. Use water under pressure and a brush to remove all slurry.
5. Clean and dry the area using compressed air.
6. Use additional cuts or additional ganged blades to widen and deepen the slots where
necessary for decouplers, sensor cable crossovers at the start point, and for overlaps.
7. Use a drill to widen the slots for the ferrite bead’s. For OC2 cable, the beads are 2.5 cm (1 in.)
in diameter. For SC2 cable the ferrite beads are 2 cm (3/4 in.) in diameter.
Application Slot dimensions
Standard slot (OC2) 14 mm wide x 6 cm deep (9/16 in. x 2¼ in.) + 2 mm, - 1 mm
(+ 1/8 in., - 1/16 in.)
Standard slot (SC2) 1 cm wide x 6 cm deep (3/8 in. x 2¼ in.) + 1 mm, - 0.7 mm
(+ 1/16 in., - 1/32 in.)
Sensor cable crossover 14 cm (5.5 in.) deep at 90º angle
Decoupler 2.5 cm wide x 10 m long x 7 cm deep (1 in. x 33 ft. x 2¾ in.)
Expansion joints or large
cracks
2.5 cm (1 in.) wide x width of crack or joint + 7.5 cm (3 in.) on
each side of crack or joint, > 30º from path of crack
Transition from slot to trench 2.5 cm (1 in.) wide sloped from 6 cm (2½ in.) to 10 cm (4 in.)
deep over 30 cm (12 in.)
Ferrite beads use a drill to widen slots for ferrite bead installation
OC2 cable the beads O.D. = 2.54 cm (1 in.)
SC2 cable the beads O.D. = 2 cm (3/4 in.)
Note Mount several diamond-tooth blades side-by-side with spacers to
achieve the recommended slot width.
Note To maintain a consistent and accurate slot width and depth, cut each
slot using a single pass of the saw (see Slot dimensions
on page 111).
Note Do not allow dust or dirt to blow into the slots.
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