Backfill

One method of reducing the ground bed resistance is to surround the rod electrodes with low resistivity soil, this work has several advantages: Reduce the resistance between conductors and soil. Provide a uniform environment so that the conductors output is predictable and constant the backfill has not organic acids and anaerobic bacteria, consequently reduces rate of corrosion in the neighborhood of rods. Petunia produces "Pet Infill" in appropriate case and polyethylene bags. "Pet Infill" is coal coke breeze of low resistivity and low ash content. The coke breeze may be treated by the addition of 10 %( by weight) of commercial grade slaked lime.

BS 7430 Clause 7.5

Soil treatment or replacement to improve earth electrode contact resistance may be used in special or difficult locations. Ecological considerations should be considered before such treatment is commenced and any deleterious effect upon electrode material has to be taken into account Such treatment may be used to advantage in rocky terrain. Where holes are bored for insertion of vertical earth electrodes, or where strip earth electrodes are laid radially under shallow areas having a low resistivity which overlay rock strata, suitable treatment will reduce the contact resistance with respect to the general mass of the ground. The use of coke breeze as an infill is not recommended as it may result in rapid corrosion not only of the electrode itself but also of cable sheaths.

To improve the conductivity of a grounding system PETUNIA recommends using Ground Improvement Material (Petinfill^TM). Petinfill^TM is a low-resistance ,non corrosice,that improves grounding effectiveness ,especially in areas of poor conductivity, PetinfilTM contains cement, which hardness when set to provide a permanent, maintenance free ,low resistant grounding system that never leaches or washes away

Material

Sodium Carbonate Activated Calcium Montmorillonite Clay. The product is a naturally occurring Substance with no Known Ecological Hazards and can be disposed of as non hazardous waste.

Packaging

Granular – polypropylene Sacks. Powder – paper Sacks.

Earthing compound – Bentonite

Bentonite can be supplied in powder or granular from and is a moisture retaining clay which is used to reduce soil resistivity.

Granular

It’s easier to handle in granular from, the powder can cause dust in windy conditions and blow away, granular is the preferred option for filling trenches where the conductor is covered with bentonite and then water poured over and mixed in the trench.

Powder

Powder is the preferred method for pouring into bore holes to ensure the mixture is a thin enough consistency to reach the bottom of the bore hole, if diamond drilling is required for deep Holes possibly 40mtrs and deeper and the bentonite is to be pumped through the core in to the hole powder would be to preferred option.

Ground Backfill Installation

1. Dig a trench at least 10.2 cm (4 inches) wide x 76.2 cm (30 inches) deep or below The frost line, whichever is deeper.* spread out enough Petinfill^TM to uniformly cover Bottom of trench – about 2.5 cm (1 inch) deep.		1. Auger a 7.6cm (3 inch) or larger diameter hole to a depth of 15.0 cm (6 inches) less than the length of the ground rod.
2. Place copper tape / earth Grid conductor on top of Petinfill^TM tm		2. Place ground rod into augered hole and drive it using the steel head and hammer approx 30 cms (one foot) into bottom of the hole. The top of the ground rod will be approximately 15.2cm (6 inches) below the level of the grade. At this time, make any connections to ground rod using CADWELD® connections.
3. Spread another 3 cm (1 inch) Deep layer of Petinfill^TM tm around and On top of the conductor so as to completely Cover Conductor.		3. Pour the appropriate amount of Petinfill^TM (see below) around the ground rod. To ensure the Petinfill^TM material completely fills the hole, tape around the ground rod with a pole.
4. Carefully cover the Petinfill^TM tm With soil to a depth of about 10 cm (4 inches), making Sure not to expose the Conductor. Tamp down the Soil, the fill in the trench.		4. Fill remainder of augered hole with soil removed during augering, For various augered hole diameters and depths, see the table below. Note: Excess standing water must be removed from the hole. Note: If premixing Petinfill^TM in a slurry form, use a standard cement mixer or hard-mix in a mixing box, wheelbarrow, etc. Use 5.5 to 7.5 litres (1 to 2 gallons) of clean water per bag of Petinfill^TM